In gasification units, the fuel quantity supplied to the gasification reactor is detected very accurately using measurement techniques. This also applies in particular to pressurized coal dust gasification units with pneumatically operating dust input systems. Prior to the initial operation of such units, functional tests and calibration experiments of the dust load flow measuring system used are needed. These examinations are to be repeated at certain time intervals as well as after long service interruptions. The implementation of such tests and examinations under as near on-site conditions as possible is desirable. Continuous plausibility checks of the dust load flow measuring systems are also expedient during the gasification operation in order to promptly detect the gradual drift of the measuring systems.
Apparatuses for implementing the necessary functional tests and calibrations using separate weighing containers are also known. Delivery takes place here from the metering vessel of the dust input system into a weighing container mounted on weighing cells.
The realization of on-site delivery conditions with operating pressures above 4 MPa (40 bar) as well as sufficiently long experiment times are nevertheless very complicated here. The setting-up of several weighing containers can generally not be avoided for multiple strand gasification units.
It is conventional for the plausibility check of determined measured values for the dust throughput to use the differential pressure between the metering vessel and the reactor. This procedure nevertheless only then supplies useable results if no changeable flow obstacles (e.g. control fittings) are contained in the dust delivery lines and as narrow a range of delivery density as possible is ensured. This method may also prove unusable or only useable to a restricted degree in the case of a change in the coal quality or in the case of a change in the granularity parameters and/or the humidity content of the gasification dust. This is disadvantageous in that measured values have to be used for the plausibility check of the dust load flow measurement, said measured values also being fed into the dust load flow measurement.